In a paint shop, process control is critical in order to insure quality standards are met. This control poses varying levels of difficulty depending on the operation being performed. One particularly challenging operation is finesse sanding and polishing performed by personnel on a painted product, typically using pneumatic hand tools, for the purpose of removal or concealment of small, yet otherwise visible defects. Generally, this operation involves first finesse sanding followed by finesse polishing of the flawed painted surface to achieve a flawless painted surface.
FIG. 1 depicts a prior art finesse polishing operation, in which a polishing tool 10 (for nonlimiting example a model 57126 Dynabuffer™ of Dynabrade, Inc. of Clarence, N.Y. 14031) is held in the hand 12 of an operator at the handle 14 of the polishing tool. When the operator presses down on an actuation arm 18 pivotally mounted on the handle 14, an internally disposed operator actuation device (i.e., an electrical switch or pneumatic valve) actuates the polishing tool, otherwise the polishing tool is not actuated. The polishing tool 10 further includes a head 20 attached to the handle 14, and a rotary component 22 at which a selected polishing pad 24 is located. As seen at FIG. 1, the polishing tool 10 is being used to polish a painted surface 26 so as to thereby impart thereto a flawless finish.
In order to obtain a desired flawless paint finish with each polishing procedure, proper finesse polishing technique must be consistently used by the operator. If the proper finesse polishing technique is not used, then small scratches will remain in the surface of the paint, which can present a dull, swirl-like defect that, although difficult to see under shop lighting, might be perfectly visible in day light. Typically, paint shop management relies on personnel training to insure operators are polishing with proper finesse technique. Unfortunately, training is time consuming and often yields inconsistent long term results.
In identifying criteria involved with a proper finesse polishing technique, there are four key control characteristics (KCCs) involved: polishing time, applied force, tool (pad) rotational speed, and polishing tool movement. With regard to polishing time, this is typically between 8 and 16 seconds, depending on the substrate temperature of the paint surface being polished, wherein as the substrate temperature increases, polishing time should also increase. With regard to applied force, too much force will flatten the waffle structure of the polishing pad and result in swirl marks in the paint, whereas too little force will not adequately remove sanding marks and also result in swirl marks, wherein a target net applied force is, for example, between about one and two pounds (by net applied force is meant total applied force of the polishing pad on the paint surface less the weight of the polishing tool, and wherein the polishing tool 10 of FIG. 1 has a typical weight of about 1.1 pounds). Next, with regard to tool (pad) rotational speed, a relationship exists (discussed in detail hereinbelow) between the tool rotation speed and the force applied by the operator to the painted surface at the polishing pad, wherein higher applied forces result in lower tool rotational speeds. Finally, the polishing pad should move across the flaw continuously to ensure full removal of sanding marks, ideally using a series of mutually orthogonal movements (i.e., x-y axes movements), wherein the pattern uses an overlap of about one-quarter of the polishing pad during each movement.
Accordingly, what would be useful in the art is if somehow a system could be provided which prevents an operator from polishing a flawed painted surface unless predetermined KCCs are met.